1. We have isolated a cDNA clone encoding the rat cartilage link protein. The 800 bp cDNA was sequenced and found to have two homologous stretches of 19 amino acids. This region also shows strong homology to the reported amino acid sequence of the bovine cartilage proteoglycan, suggesting a common role for these sequences in binding to link and proteoglycan. 2. We have isolated cDNA clones for the mouse laminin A, B1, and B2 chains. The nucleotide sequence of a 5.5 Kb cDNA insert for the B1 chain was determined. Computer analysis of predicted protein secondary structure suggests that the B1 chain has at least four distinct structural domains. 3. We have isolated a series of overlapping genomic clones which span about 60 Kb encoding most of the B1 chain of mouse laminin. The gene structure was examined by electron microscopic analysis. The gene shows an unusual clumping of small exons separated by large introns. 4. We have isolated a series of overlapping genomic clones for the human type II collagen. The nucleotide sequence of the promoter of this gene shows a strong homology to those of the rat type II collagen gene. 5. We determined the nucleotide sequence of eight exons coding for the helical part of the mouse Alpha-1 type IV collagen. The size of these exons suggest that the gene for Alpha-1 type IV collagen evolved separately from the interstitial collagen genes. 6. We have constructed recombinant plasmids in which type II collagen promoter determines the level of an E. coli enzyme, cholramphenicol acetyltransferase. Transfection of these plasmids to chick chondrocytes reveals that the sequence upstream from -380 is necessary for the efficient transcription of the type II collagen gene.